There are known tape drive mechanisms that thread tape from a single reel cartridge onto a take-up reel. Certain mechanisms utilize a dual hub take-up reel design having an inner hub and an outer hub. The inner hub is concentrically located inside a hollow outer hub. The inner hub is secured rigidly to the motor spindle and the outer hub is free to rotate about the inner hub by a bearing. A flexible leader is fixed to the inner hub, the flexible leader leaving the inner hub surface tangentially and passing through the outer hub through a slotted opening. The flexible leader is attached to a linking body designed to connect and disconnect the end of the tape leader from the single reel cartridge. This slotted opening in the outer hub is configured to allow the leader to pass through, but not the linking body. The configuration of the linking body is matched to the outer surface of the outer hub so that when the linking body is pulled into the outer hub, a continuous cylindrical surface is formed on the outer hub.
As the inner hub rotates, the leader wraps around itself. Tension is maintained in the leader by motor control at the cartridge reel. The tension in the leader prevents the outer hub from rotating. Eventually, the linking body is pulled into the cavity, forming the continuous cylindrical surface on the outer hub. The outer hub now rotates with the inner hub under tension from the leader. This continued rotation wraps tape from the single reel cartridge around the outer surface of the outer hub.
In the above described tape mechanisms it is critical to maintain tape tension at all times. This is normally accomplished by carefully controlling the two reel motors so that their speeds are nearly perfectly coordinated. Depending on which direction the tape is moving, each reel changes roles as supply and take-up. In the case where the dual hub reel is a take-up reel, operation is relatively smooth because the flexible leader is under tension. In the supply role, however, the inner hub attempts to control the outer hub by pushing on a flexible member (i.e., the flexible leader). In order to maintain the necessary tension both in the tape and the flexible leader, the inner hub has to operate as a brake. Acceleration and change in tape direction is limited by the inability to utilize the motor to its full capability, since the motor is only operating as a brake. In the data recording industry, time is very important. Because of that, limitations on acceleration and change in tape direction and increase in access time are particularly undesirable.